Apparatus for controlling the power output of gas turbine plants



W. TRAUPEL FOR Jan. 12, 1954 2,665,548 APPARATUS coNTRoLLING THE POWER OUTPUT oP GAS TURBINE PLANTS 2 SheeTs-Sheet 1 Filed June 24, 1950 Jan. l2, 1954 w. TRAUPEL 2,665,548

Y APPARATUS FUR coNTRoLLTNG THE POWER OUTPUT oF GAS TURBINE PLANTS 2 Sheets-Sheet 2 Filed June 24, 1950 Patented Jan. l2, 1954 l i n l UNITED STATES* PATENT oI-Ficsl APPARATUS FOR CON TROLLING y yTHE POWER OUTPUT OF GAS TURBINE PLANTS Application June 24, 1950, Serial N0. 1"70,1.48

Claims-priority, application Switzerland June 30, 1949 14 Claims. (Cl. 60-39.15) l 2 The present invention relates to an apparatus third of the speed at which `average changes for controlling a gas turbine plant having at occur, electactuation of the pressure control least one turbine producing useful work and ,at whereby a load variation ofgreater duration is least one gas turbine, which is mechanically ineventually compensated bythe pressure reguladependent of the first turbine and drives a comtion, and `a change of the temperature of the pressor. working medium, which may have occurred, is It is known to control the output of gas turbine annulled by a reduction or increase in the turnplants by regulating the heatsupply to the workover of the operating medium in the plant. ing medium circulating through the plant and The apparatusaccording to the invention comby controlling also the pressure conditions in the prises heat supply control means for controlling plant. This conventional method is not satisheating of the working medium before it enters aCOlY, particularly not in plants for driving frea turbine, a device for controlling the pressure quency controlled electric generators supplying in the plant. an impulse `giver or producer which alternating current power systems. Such sysis affected by an operating condition of the prime tems serve a number of individual consumer l5 mover, impulse transmittersfor transmitting the groups which are independent of one another, pulses from said producer to the heat supply conand the load on such systems increases and detrol means and to the pressure control device, and creases rapidly at Certain periods, and hCreaSeS a delaying device interposed in the transmitter slowly and remains steady at others. The curbetween the impulseproducer .and the pressure rent generators, however, must maintain an excontrol device. actly regulated frequency at all Atimes and de- The combustion chamber for supplying heat to mand maintenance of a constant speed of the the working medium may comprise control means prime movers operating the generators. for supplementally controlling theheat supply Modern gas turbine plants have numerous conin dependence on the pressure of the working duits and large heat exchangers for obtaining a medium in or near the combustion chamber. high thermal eliiciency and consequently con- This may be done by providing a pressure contain a large volume of Working medium. A controlled valve means in the fuel supply conduit 13101 apparatus involving COIltihual rapid changes to the combustion chamber. In gas turbine of the pressure ofthe Working medium for satS- plants in which atleast one turbine comprises fying load liuctuations of short duration entails a conduit by-passing at least the iirstturbine great IOSSSS, because it COIlthually changes the stage, the pressure control means may actuate energy content of the plant. The pressure in the `a valve means in said 'by-pass conduit.

plant can be changed only slowly because of its The aforementioned delaying device may congreat internal volume. It is therefore necessary sist -of a throttling means in the impulse transto compensate rapidly passing load variations by mitter conduit. If the impulses are transmitted Changing the heat supply to the working medium i5 by way of anuid, the delaying device may consist before it enters the turbines. Such a control has of an air chamber communicating with the transthe disadvantage that the temperature of the mitter conduit.

working medium is-changed. A reductionof this Further and other objects of the present invenu temperature during long periods reduces the thertion willvbe hereinafter set forth in the accommal efeerlCY Of the plant, and ihCTeaSe OfA the 40 panying specification-and claims, and are shown temperature is limited by the heat resistance of in the drawings which, by way of illustration,

the blahgmaterial of the turbines. show what I/now consider to be preferred em- It is an object of the .present invention to probcdiments of the invention. vide a control apparatus which avoids the afore- `In thedrawngs:

mentioned disadvantages and which .is charac- Fig, -1 is .a diagrammatic lay-out of a plant terized by a regulation-of the heatsupply to a ccordingtothe invention;

heater for the working medium, from which the FigfZ vis a diagrammatic vlay--out of modied medium enters one of the turbines, in direct de- .plantaccording to the invention.

Dendence on .an Operating Condition Gf the prime Referring'more particularly to Zelig. l of the mover, and by regulating the pressure condidrawings,..l .designatesa compressor drawing air tion in the plant in dependenceon the same con- :from ,conduit 2 and forcing it through conduit 3 dition but delayed with respect to the regulation into the space ksurrounding tubes @l of heat exof the heat supply. This delayed action has the changer 5. Av portion .of the` air pre-heated in effect that only relatively slow changes of load, heat exchanger 5 is further heated in heat exi. e. changes whose .speed s,.say, less. than one changer 6 and united with the other portion,

which is not further heated, in conduit I. A portion of the so pre-heated air news through conduit 8 into the space surrounding tubes 9 of a gas heater IE, the other portion flowing through conduit i I into the combustion chamber I2 of the heater Iii. The air now-ing through conduit 3 and heated by the tubes 9 passes through a conduit I3 into turbine i4, expands therein, and is conducted through conduit I5 into the tubes 4 of heat exchanger 5, in which a portion of the heat still contained in the air after its expansion is transferred to the air from conduit 3, which air was compressed in compressor I. The expanded and cooled air flows from the heater 5 through conduit I6 to a cooler I'I and recirculates through conduit 2 into the compressor I.

A portion of the air removed through conduit II from the above described circuit serves for burning fuel supplied through conduit I8 which is finely divided in nozzle I9. The fuel supply is controlled by a valve means 2l inserted in conduit I8 and actuated by a servomotor 20. The hot mixture of air and combustion gases flows through the tube system 9 of the gas heater IG and transfers a part of its heat to the air coming, through conduit 8, from the heat exchangers i and Ei and fiowing around the tube system 9. The so cooled gas mixture enters the charging turbine 22, is expanded therein to an intermediate pressure, and conducted through pipeline 23 into a gas reheater 24. Here, a part of the oxygen still contained in the mixture is used for burning fuel supplied through conduit 25 and finely divided in burner 2S. The amount of fuel supplied is controlled by valve means 21 in conduit 2t. The reheated gas mixture is conducted through pipeline 29 into turbine 3B where it is expanded to substantially atmospheric pressure for producing power and driving a machine 3l, which is, in the example illustrated, an alternating current generator.

The'exhaust gases from turbine 3B are conducted through tube system 33 of heat exchanger 6, where a part of the heat still contained in the mixture is transferred to a part of the air circulating through the circuit described supra and compressed in compressor l, Thereupon the mixture leaves the plant through an exhaust conduit 34.

To replace the air withdrawn through conduit II air is drawn from the atmosphere by a charging compressor which is driven by the charging turbine 22, and introduced into the cycle, in compressed state, through conduit 35.

For adjusting the amount of working medium flowing through the prime mover turbine 30, a valve means 3S is provided in a passage 3'! bypassing the rst stages of the turbine, and a further valve means 39 is provided in conduit 22. Valve means 38 is actuated by a servomotor lo and valve means 39 is actuated by a servomotor t!- I both servomotors being operated by an operating medium, for example oil, conducted thereto by impulse transmitting conduit 42. The pressure of the oil is regulated by a control device, surrounded by a dash-dot line and designated by I in Fig. 1. This control device is contained in a casing 43, te@ and is actuated by the pressure of the working medium in the exhaust line of the charging compressor 35, which pressure is transmitted to the control device by means of conduit ad. The elasticity or constants of springs Fri and ifi counterbalancing the pistons in servomotors do and lll, respectively, are so chosen that a gradual increase of the pressure medium Y in conduit 42 will actuate servomotor 3l to fully open valve 39 before valve 3S is opened by servomotor to. Increase of the flow area in pipeline 23 caused by opening valve 39 and in passage 3l' due to opening of valve 38 reduces the pressure at the outlet of vcharging turbine 22 and increases the heat drop available in said turbine. This causes speeding up of turbine 22 and of the charging compressor driven thereby and consequently an increase of the discharge pressure of the compressor; vice versa, a reduction of the aforementioned flow areas causes a reduction of the discharge pressure of the charging compresser.

A starting motor IBS is provided for driving compressor I for starting the plant.

Turbine I, which drives compressor I, for controlling circulation and pressure in the air circuit, is provided with a passage tl Icy-passing the first stages of the turbine, and the flow of air through the passage is controlled by valve means EB. The latter is operated by a servomotor 49 which is actuated by a pressure fluid,

Yfor example oil, in impulse transmitting conduit 5%, which is connected with the servomotor. The pressure of the uid is controlled by a control device II, which is actuated by impulse generator III. Device II is Vcontained in casing IIS, ia, as is device I.

The fuel supply to burner 26 of the gas heater 24 is controlled by actuation of a lever 5I which is pivoted to the stem of valve 21 which may be constructed similarily to valve I'I8 of the system illustrated in Fig. 2. The left end of lever 5I is movably connected with piston I2I of servomotor 52. The chamber above piston I2I communicates through conduit 53 with the inlet of charging turbine 22. The chamber below the piston is connected, through conduit 5a, with the impulse generator III and is filled with uid whose pressure is controlled by the impulse genn erator. Piston I 2i is yieldingly forced into middle position in its cylinder by means of a spring 55. The right end of lever 5I is connected with piston I22 of servomotor 55. The chamber below piston I22 communicates with the reheater 2d through conduit 5B, and the pressure in the chamber is counterbalanced by spring 51.

The fuel supply to gas heater III is adjusted by operation of valve 2i which is actuated by a servomotor 20 which communicates through conduit SE with the interior of pipeline I3 and is therefore responsive to the admission pressure of turbine I4. This pressure acts on the top side of a piston in the servomotor and is counterbalanced by a spring.

'Ihe impulse generator III is actuated by a centrifugal governor driven by the shaft of the machine 3l. Sleeve 6I of the governor El] is connected with a piston valve 53 by a spring 62. This valve controls, in the conventional manner, admission and relief of a control fluid to and from a conduit below the valve according to the tension of spring S2, which is controlled by governor 69. The control fluid, for example `oil, is supplied to the valve through a conduit (it and leaves the valve through a conduit 65, conduit te being supplied from a source of fluid having constant pressure, which source is not shown as this is conventional and not part of the invention.

Each change of speed of the machine 3I caused by a change of load on the machine effects a change of pressure of the control fluid below valve S3: this pressure is transferred through conduit 13 to the chamber below piston I2I of servomotor l52. The latterv actua-tes yfuel1 supply vvalve v'-21 Lin ted to remain at itsxso Iadjusted value Lbecause a Y'greatlyincreased"temperature causes A-toornuch thermal stress `on `the `turbine 4bladesand a much lowered temperature reduces the eiliciency of the `power plant. ."Therefore, .according to the invention, every :change of load :is subsequently controllecl 'by changing the pressure .of the work- `ing medium.

For 'accomplishing the V'aforestated `object of the invention, thev pressure ofthe vcontrol fluid,

which lis adjusted vby slide valve S3 in dependence on the speed oftheprime mover, is supplementally` controlledby. a throttle lmeans '56 fand transrnittedlthrough a conduit .el to the top side of spistonisrof servomotor 69. Throttle fst vcauses .a delay 'of vthe'transmission or the `control irnpulsesfgeneratedin device IIIto regulator II, so that piston @s @is displaced slowly and regulator II is actuated only 'if the load remains changed. Piston '68 vdisplaces a cam 'il With which it is connected byrneans or a piston rod'it. `Cam 'li actuates a `follower l2 which Ais connected .with a vslide valve ill by ymeans of a spring i3.

Compression Yof the llatter and consequently the position of valve 'Hl depends on the position lof cam il. Valve "ifi controls the supply and discharge foi a control fluid through conduits 'l and ll, respectively, tofand from the cylinder chamber of a servomotor 75, which chamber is closed by a piston 18. The pressure ofthe working medium operating charging turbine 22 acts on the distal side of piston i8, the pressure being transmitted to piston "lll Aby means V:of -a conduit i9; at steady load conditions, 'piston 78 is held in its lmiddle position by springs 80 and 8l. Piston 18 actuates a pressure fluid control valve 8i.V

of va servomotor comprisinga piston-83. vFor this purpose, Apiston rod 87 pivotally supports a lever 85,- oneA arm of which is connected by 'rod -89 withvalve E2 and the other arm of which is connected with piston'li via `a dashpot device 84, comprising a piston 85 and a throttle!!! in the connection between the piston chambers. Valve 82 controls now of control :fluid from conduit lill into the 4chambers adjacent to piston 83. Conduit Si! is conectad with a source of a control Ihuid whose pressure is maintained in theA conventional manner. Spring 88, one end of which is connected with the arm of leveri connected with piston 83 vand the other end ofv which is fixed to `casing lit, tends to return valve 82 to its neutral position, whereby piston 85 moves relative to cylinder 8f3 yand piston 83stays in .theadjusted position. `lviovementprpiston 85 is dampenedlby the throttle 9 l.

The aoredescribed yielding return motion, which prevents over-regulation vand hunting, comes tore'st Aonly if 'the vdevice is :in neutral position, i. e. if thepressure at the inlet of turbine-22 is the same as the pressure of the control 'fluidA at Ythe left side ofpiston T18. Piston '83 isconnected byirneans-of Ka piston vrod' with i-a spring Stand .the latter with a slide valve'93 controlling ilow' offacontrol uid through a conduit se and returnthereof to its source through conduit', toand .from one side of a piston in servomotor rlllwhich .is connected with 'Valve' 93 byimeans of conduit 553. Conduit'iiii is connected to a'fconventicnal source of supply of operating uid `under constant pressure, and conduit 95 retumsfthefiiuid to said source. Cam 'Il is so shaped rthat the pressure of the control iiuid in conduitt, .uponactuation oi valve 93, increases lif rodi@ moves ldownward because of increased pressure.abovefpiston' causing cam follower 'i2 to actuate valve irl torincrease the pressure on theleftslde of piston i8. Increased pressure in conduite@ causes opening of valve 48 in by-pass fill' of :turbine l `and speeding up of the latter and of compressor l driven thereby. This causes increase of pressure of the working luid in the primary lor .air cycle and subsequently in the Whole plant, increasing the output of the plant. Downward movement of rodV lil was due toa eereased speed of prime mover iii." This speed is vnow brought back to normal. Vice versa, increase `of the speed of the prime movercauses a reduction'of the pressure in conduit 5e, closing of valve'lt, slowing 'down of turbine I4 and ci' compressor I, and consequently reduction of the pressure of the working iiu'id lin the entire plant.

The pressure 'in the yair cycle of the plant, Which'isregulated. as described in the paragraph next above,v acts through conduit @t on the piston of servornotor'ZB of `fuel valve 2i and increases -and reduces the fuel supply to gas heater iii depending on ywhether the pressure oi the working medium is increased or decreased. The

' pressure of the'wor'lfzing medium acts on the pistons or servorno'tors 52 and 'do through conduits 53 and *59; increasing pressure returns these pistons to their neutral positions.

The right-side of the piston chamber in servomotor 'l5 of `regulator -II lcommunicates with the right side `o Apiston chamber H33 of regulator I vand with conduit'lsy which transmits the pressure of the working'fluid `at the inlet oi charging 'turbine '22 to the regulators. Piston Se is connected through piston rod ist, lever EQ2 pivoted thereto, and rod i915 pivoted to lever |92, with .a' piston valve et controlling flow of control vfluid from conduit *SS selectively to the sides or" `a servomotor piston itu and returns the uid inlconventional manner to the source from which conduittll is supplied. Piston lei? is rigidly connected with dash-pot-cylinder itl containing piston .illt'which .is connected to lever IGZ. Movement of piston Viill in cylinder itl is retarded by `throttle 407i in a `conduit connecting the parts of the cylinder-chamber .at yboth sides of the pis ton. A. spring wil interposed between lever 92 andcasing (i3 tends to return lever 82 and valve et* to neutral position, Piston I llt is thereby moved relative to cylinder It! and piston stays in its `adjusted position.

AMovement of piston lui) causes a change of the tension of spring me, to which it is connected by rod 1:08, and of the position of piston valve lll) which controls'ilow of control iiuid through conduits A$34 and e5 to land from conduit A2. The latter is connected with servomotors 45 and 4l individually v'comprising return springs t5, t respectively, which are soadjusted that a gradual riseoi the pressure inconduit i2 causes opening of valve 38 and an increased iiow of working medium*throughiby-pass 31 of turbine 3s only after throttle valve 39, which is actuated by servomotor 4|, has been fully opened. Movement of piston 93 to the left, as seen in Fig. l, actuates the described part of regulator I in such a way that the pressure in conduit 42, adjusted by valve H5, increases; this pressure decreases upon movement o piston 98 to the right. Consecutive opening of valves 39 and 38 caused by increasing pressure at the inlet of charging compressor 22 causes a decrease of the pressure of the Working medium at the outlet of turbine 22 and an increased speed of said turbine and of the compressor 35 driven thereby, whereby the pressure of the charging air is increased.

Vice versa, upon a reduction of pressure at the inlet of turbine 22, regulator I closes valves 39 and 38, thereby raising the pressure at the outlet of turbine 22 and slowing up its speed and that of charging compressor 35, whereby the pressure of the charging air is reduced.

If the plant operates at steady conditions, piston 38 is held in its middle position by means of springs and 9T.

The pressure of the charging air which is adjusted by regulator I in the manner described above acts through conduit Be on the upper side of piston ||3 of servornotor lili forming part of regulator I, and moves the piston against the action of a spring H5. Piston ||3 has a cam I connected thereto by piston rod i6, the cam actuating cam follower I IS. The latter actuates, via a spring i9, a slide valve |25 which controls flow of a control fluid to and from the left side of piston 98 through conduits 1S and l1, respectively. Conduit 'ii receives fluid at constant pressure from a conventional source and conduit 1'! returns it thereto. Piston 93, which has been moved to the left by the rising pressure at the inlet of turbine 22, is thus returned to its neutral position upon an increase of pressure at the outlet of compressor 35.

Regulators I and II come to rest only when the servomotor pistons I8 and 93 are in their center or neutral positions. This is accomplished if, after a change of speed of prime mover 3| caused by a change of load thereon, the pressure of the working medium of the plant is adapted to the new load condition, by the described control steps.

Each change of pressure of the working rnedium in the intermediate gas heater 24 is transmitted through pipeline 53 to the bottom side of piston |22 of servomotor 56. The latter adjusts the fuel supply to heater 24 for steady load conditions. During the change from smaller to greater output, regulator III causes increased flow of control uid through conduit 54 to the lower side of piston |2|. This moves the piston upward and effects immediate increase of fuel supply through conduit 25 to heater 24 by opening fuel valve 21. The pressure of the working medium of the plant which is controlled by actuation of valves 28, 39 and 38 rises gradually and the pressure of the medium at the inlet of turbine 22 transferred through conduit 53 to the upper side of piston |2| returns the piston towards its previous position and reduces the fuel supply to heater 2 by closing valve 2l. In the meantime, the pressure in heater 2li has increased and acts on the bottom side of piston |22, thereby opening valve 21 and increasing fuel supply to heat the increased amount of working medium passing through the heater. Fuel supply to the intermediate gas heater is thus controlled by the application of two subsequent control steps.

The pressure at the outlet of turbine 22 is also regulated by two control steps. Opening of valves 39 and 38 causes a lowering of this pressure, whereas the described control steps cause an increase of pressure in the entire plant eventually increasing the pressure at the outlet of turbine 22. The last mentioned increase of pressure exceeds the previous decrease. The pressure drop in the charging turbine 22, however, is increased because the pressure at its inlet is increased also.

A sudden increase of fuel supply to heater 2li for satisfying a sudden increase of load is permissible only within certain limits which are set by the temperature resistivity of the turbine blade material. In a plant which must absorb sudden load fluctuations, special provisions should be made to immediately increase the energy content of the plant. For this purpose, an air accumulator |23 is provided, from which compressed air can be blown into the circuit by opening a valve |24. This valve is operated by a servomotor |25 whose piston |26 is actuated by control fluid from conduits |27, |2la.

If a sudden slowing up of the machine 30 causes regulator III to move valve G3 for increasing the pressure of the control fluid in conduits 54 and |2'|, this increased pressure first lifts piston |2| of servomotor 52 to its extreme upper position. If the fuel supply increased thereby does not suffice to bring the speed of machine 3l! back to normal, the pressure in line |21 will continue to rise until it can move piston |26 against the action of spring |28. This causes opening of valve |24 for admission of compressed air to theV air circuit of and increasing the pressure in the plant.

Provision must also be made for preventing machine 3i) from running too fast upon a sudden decrease of the load thereon. Two additional servomotors |23 and |30 are connected with conduit |21 which control a relief valve |3| and a valve |32, respectively, in pipeline 23. If, due to a sudden increase of speed of the prime mover unit 30, 3|, the pressure in conduit |21 falls, relief valve |3| is opened and valve |32 is closed. This decreases or interrupts the supply of operating medium to turbine 35.

The invention provides a quickly responsive control which does not impair the operating efficiency of the plant, by compensating small and quickly passing load fluctuations by changing the heat supply to the working medium. This change has an immediate elect, whereas the pressure of the working medium changes slowly and follows load variations only at a great time lag. Losses caused by a quick change of the pressure conditions of the plant due to continual changes of the energy content of the plant are avoided by the system according to the invention.

The invention can be used also in connection with an open-cycle gas turbine plant as illustrated in Fig. 2. In this plant, air is drawn from the atmosphere by a compressor |22 and the compressed air is blown through pipeline Uil into heat exchanger |42 and therefrom through conduit |23 into the combustion chamber of gas heater |42. A portion of the oxygen of the air is used for burning fuel which is supplied to the gas heater through conduit 25 and burner H16. The working medium, heated to a high temperature in heater |645, is divided into a stream iiowing through conduit |47 to the prime mover turbine |48 and into a stream flowing through conduit |50 into an auxiliary power turbine |5|.

The portion of the working medium ilowing through turbine |48 is expanded to substantially atmospheric pressure and thereby produces power to operate a machine |49 which, in the illustrated example, is an alternating current generator.

The portion ci" the Working mediuml owing through turbine I is also expanded Vto substantially atmospheric pressure and produces power for driving compressor Hill.

Both portions of the working medium are reunited in conduit |52 and conducted into heat exchanger |42, where a portion of the heat still contained in the working medium is used for preheating the air entering' the heat exchanger through conduit lill. medium leaves the plant through exhaust duct |53. Y

For regulating the fuel supply -to heater |44; a control means Ht is interposed in conduit |45;

this control means is operated by a servomotor- |54 whose piston |55 is actuated by pressure fluid supplied through conduit |56. The pressure of this iluid is regulated by an impulse producer device IV, which is surrounded by a dash-dot line in the diagrammatic showing of Fig. 2.

For starting the plant, a direct current electric machine |51 is connected with compressor |453. Its brushes can be displaced by means of a rod |58 actuated by a servomotor |59. A movement of servomotor piston |60, to which rod |58 is connected, in the direction indicated by -linv Fig. 2, changes the operation of the machine from that oi a generator to that of a motor. The electric current is supplied to and taken from machine |51 by conduits ll which are also connected with a second direct current machine 62 which is connected for rotary drive with the machine |45. This permits exchange of energy between the prime mover group |48, |49 and the compressor group |40, |5|, the latter being `supplementally driven by power produced in the former or the former receiving power from the latter, depending on the setting of the brushes of machine |51 for operation as a motor or as a generator.

servomotor |55 is actuated by pressure'im* pulses produced by impulse producer IV in a control fluid conducted to and from the upper side of piston |63 by conduit |63. |64 inserted in the latter and a pressure cham- Thereupon the working A throttle means Y CTI ber communicating with conduit |63 between the throttle |55 and the servomotor 59 cause delay of transmission of control impulses from the impulse producer to the servomotor |59.V

The current produced by generator |49 is conducted to a power system 51 by conduits |66.

A resistance |58 is interposed in one of the conduits 65, the resistance being short-circuited by a coil 69 of a solenoid having a core |10. The latter moves a soft iron bolt |12 against the action of a spring |13 depending on the tension drop in resistance |68. Each movement of bolt |12 is transferred by 'a second spring |14 to a slide valve |15. control iiuid from a source, in which the pressure of the fluid is maintained and which is not shown as it is conventional and not part of the invention, through a conduit |16 and return of the iluid to the source through conduit |11, to

The latter controls flow of av and from conduit |56. The pressure of the fluid Y 10 ance I 68l caused-v byincreased load on system |61, causing reduced fluid pressure below valve |15, which pressure is transmitted through conduit |56 to the top-side of piston |55 of servomotor |5411 and causesopening of fuel valve |18V and instant increase of fuel supply to heater |44. Vice versa, decreasedload on system |51v produces instantaneously areduction of fuel supply to the heater. EachI change oi load on prime mover group |48, |49 is thus instantaneously compensated by a change of temperature of the working medium operating turbine M3, as well as the. compressor turbine |51.

In` a plantaccording .to Fig. 2, asin the plant shown in Fig. l, itis not permissible to maintain the so regulated temperature until, by chance. another change oi' load re-adjusts the Vtemperatureoffthe working. medium tothe desired value,

because a. sustained excessively high temperature causes undue. thermal stresses 1n the turbine blad.-

ingi and an excessivelylow temperature reducesv isfled by changing theV pressure of the. operating,

medium, whereby the previously changed tern- Iperature is. brought back to normal. For this purpose, the pressure of the control'iluid which Wasadjusted `bythe actuation of slide valve |15 independence on the load on generator |49 is transferred through conduit |63, to the upper side of piston |55 of servomotor |59. This transfer, however, isdelayed by throttle means |64 and pressure chamber |65. Displacement vof the brushes of machine |51 is therelore effected slowlyand gradually.

Upon lowering of the pressure in conduit |55 by. the. impulse producer IV because of an increase 0I the load on generator M9; piston I of servomotor |55 is slowly moved upward and the brushes of the direct current machine |51 are moved to change its operation from that of a generatorto load on the primemover unit causes slowing up of the compressor unit and a gradual reduction of the pressure and of the turn-over oi the workingmedium, whereby the previously lowered temperature is returned to normal. By proper choice of the compressor characteristic, the temperature vof the working medium can be controlled supplementally in dependence on the circulated volume of working medium so that, also at partial loads, the. temperature of the Working medium at the inlet of the turbine is such as to permit eiilcient operation of the turbine.

In the embodiment of the invention illustrated in Fig. 2 and described above, small and quickly passing load iiuctuations are compensated almost instantaneously by a change of the amount of heat supplied to the plant, whereas the pressure conditions in the plant are changed slowly and follow changes of load at a substantial time lag, as is the case in the systemV according to Fig. kl. In this way, by a4 continual change of the energy content of the plant working medium at quickly passing load variations,

losses are avoided, which are caused l due to changes of pressure of the The invention is not limited to the embodiments shown in Figs. 1 and 2. A person skilled in the art can apply the described control apparatus without difliculty to a fully closed-cycle gas turbine plant having at least one outside power turbine and at least one compressor turbine mechanically independent of the outside power turbine. The apparatus according to the invention can also be used in plants for driving a ships propeller or a vehicle or machines other than those in the examples illustrated and described.

Though a compressed control fluid is employed in the illustrated embodiments of the invention for actuating the new control apparatus, the apparatus can be actuated as well by mechanical or electrical means.

I claim:

1. Apparatus for controlling the power output of a gas turbine plant, comprising a compressor for compressing the working medium of the plant, means for driving said compressor, a heater connected for medium flow with said compressor and heating the compressed medium, heat supply control means for said heater, a turbine connected for medium flow with said heater and expanding the compressed and heated medium for power production, a control impulse producer connected with and being responsive to the load on said turbine, a rst control means connected with and actuated by said producer and connected with said heat supply control means for controlling the heat supply to said heater, a second control means connected with said producer for actuation thereby and connected with and controlling the means driving said compressor, and an impulse retarding device interposed between said producer and said second control means for delaying actuation thereof and of the control of the means driving the compressor relative to the control of said heat supply control means by said iirst control means.

2. Apparatus as dened in claim l, comprising a pressure responsive means connected with said heater and responsive to the pressure of the working medium thereat and connected with said rst control means for supplementally controlling said heat supply control means in dependence on the pressure of the working medium heated in said heater.

3. Apparatus as defined in claim l, comprising pressure control means responsive to the medium pressure in the plant, medium flow control means interposed in the path of the working medium between said compressor and said turbine and connected with said pressure control means for controlling the iiow of the working medium through the plant in dependence on the medium pressure.

4. Apparatus as set forth in claim 3, said pressure control means being also connected with said rst control means for actuating it supplementally to the pulses produced by said impulse producer.

5. Apparatus for controlling the power output of a gas turbine plant, comprising a compressor for compressing the working medium of the plant, a first multi-stage gas turbine driving said compressor, a heater connected for medium flow with said compressor and heating the compressed medium, heat supply control means for said heater, a second multi-stage gas turbine mechanically independent of said irst turbine and connected for medium ilow with said heater for producing outside power by expanding the compressed and heated medium, a control impulse producer connected with said second tur-4 bine for producing control impulses in dependence on the load on said second turbine, a nrst control means connected with said producer for actuation by impulses produced thereby and connected with said heat supply control means for controlling the heat supply to said heater in dependence on the pulses produced by said producer, a by-pass on at least one of said turbines for by-passing working medium around at least the rst turbine stage, a medium flow control device in said by-pass, a second control means connected with and actuated by said producer and connected with said now control device for controlling it in dependence on the pulses produced by said producer, and an impulse retarding device interposed between said producer and said second control means for delaying control of said flow control means relative to the control of said heat supply means.

6. Apparatus for controlling the power output of a gas turbine plant, comprising a compressor for compressing the working medium of the plant, means for driving said compressor, a hea*- er connected ior medium ow with said compressor and heating the compressed medium, heat supply control means for said heater, a turbine connected for medium flow with said heater and expanding the compressed and heated medium for power production, a control impulse producer connected with and being responsive to the load on said turbine, a rst control means connected with and actuated by said producer and connected with said heat supply control means for controlling the heat supply to said heater, a regulator for the means driving said compressor, and impulse retarding means connecting said impulse producer and said regulator for actuating the latter by the former delayedly in relation to the control of the heat supply to the heater, said regulator comprising means responsive to the pressure of the working medium in the plant for effecting actuation of said regulator in addition to said impulse producer.

7. Apparatus for controlling the power output of a gas turbine plant, comprising, in combination, two mechanically independent turbo-compressor units for compressing the working medium of the plant; a gas turbine mechanically independent of said units and receiving compressed working medium therefrom for producing outside power; heating means receiving compressed medium from said units, heat supply control means for said heating means; a control impulse producer responsive to the load on said gas turbine and connected with Vsaid control means for actuation thereof; impulse retarding means connected with said producer, a regulator for the pressure of the working medium of the plant connected with said retarding means and adapted to be operated by retarded control impulses from said producer; and a second regulator for the pressure of the working medium of the plant actuated by the pressures of the working medium produced by said units.

8. Apparatus as dened in claim '7, said first regulator being connected with and regulating one of said turbo-compressor units and said second regulator being connected with the other of said units or regulating the pressure of the working medium produced by the compressor of said other unit.

9. Apparatus for controlling the power output of a gas turbine plant, comprising a compressor 13 for compressing the working medium oi the plant, a rst gas turbine driving said compressor, a heater connected for medium now with said compressor and heating the compressed medium, heat supply means for said heater, a second gas turbine mechanically independent ci" said iirst turbine and connected for medium now with said heater for producing outside power by expanding the compressed and heated medium, a control impulse producer connected with and responsive to the load on said second turbine, control means connected with said heat supply means and with said producer to be actuated thereby, impulse retarding means connected with said producer, a regulator connected with said retarding means and adapted to he actuated by retarded control impulses from said producer and connected with one of said turbines for regulating the operation thereof, and a second regulator responsive to pressure conditions of the working medium of the plant and connected with the other turbine for regulating operation thereof.

10. Apparatus as dened in claim 9, comprising by-pass means connected with at least one of said turbines for ley-passing Working medium around a iirst stage thereof, and valve means interposed in said by-pass and connected with one of said regulators to be operated thereby.

11. Apparatus as defined in claim 9, comprising a conduit :for supplying Working medium to one of said turbines, and valve means interposed in said conduit and connected with one of said regulators to be operated thereby.

12. Apparatus for controlling the power output of a gas turbine plant, comprising a compressor for compressing the Working medium of the plant, means ior driving said compressor, a heater connected for medium flow with said compressor and heating the compressed medium, a

turbine connected for medium flow with said heater and expanding the compressed and heated medium for power production, a pressurized control iiuid conduit, pressure. control means responsive to the load on said turbine and interposed in said conduit for regulating the pressure or the control iiuid therein in dependence on the load on said turbine, heat supply control means connected with said heater and comprising a rst servomotor connected with said control fluid conduit and being responsive to the pressure of the fluid therein, regulating means for the means driving said compressor, a second, iuid pressure responsive, servomotor connected with said regulating means and with said uid conduit for actuating said regulating means accordance with the pressure of the control iiuid in said conduit, and control fluid iow retarding means connected with said conduit between the points where said servomotors are connected to it for delaying actuation oi the second servomotor relative to the actuation of the first servomotor.

13. Apparatus as defined in claim 12, said iuid ow retarding means consisting of a throttling device interposed in the control fluid conduit.

i4. Apparatus as defined in claim 12, said iluid iow retarding means consisting of an air chamher communicating with said control fluid conduit.

WAL'I'ER 'IRAUPEL References Cited in the file 0f this patent UNITED STATES PATENTS Number Name Date 2,372,686 Sdille Apr. 3, 1945 2,459,709 Lysholm Jan. 18, 1949 2,544,235 Pfenninger Mar. 6, 1951 40 2,581,276 Mock Jan. 1, 1952 

